Here’s what we know for certain about Mike Napoli: He is not a member of the Red Sox.

That’s one of the few facts at our disposal in a story that has seen the principals journey deep underground and basically off the grid, leaving the rest of us to nibble at the periphery in search of clues.

It has been more than three weeks since the Red Sox reached agreement on a three-year, $39 million deal with Napoli, who was clearly their No. 1 target in free agency.

It has been more than two weeks since they scrapped his introductory press conference because of concerns raised during his physical, reportedly over the condition of his hip, though neither the team nor Napoli’s camp has confirmed the cause of the holdup.

The sides have privately spent the ensuing time crafting a solution, whether it’s augmenting the contract to protect the team in case of an extensive injury, or shortening the deal to two years.

Now comes word, via Jen Royle of SBNation, that the Red Sox are actively engaged with free agent first baseman Adam LaRoche, a 33-year-old coming off a better year than Napoli, but who also will require draft pick compensation in the form of the Sox’ second-rounder (not to mention that accompanying portion of the Sox’ bonus pool).

So what are we to make of all of this? Considering how aggressively the Red Sox pursued Napoli this winter, it’s safe to say they’re making every effort to sign him. The fact that they haven’t flat-out walked away suggests they believe the deal can be salvaged, and that Napoli will not, in fact, turn into another Mike Lowell or A-Rod and suffer a debilitating hip injury.

Equally telling — if not more so — is the fact that Napoli has not been linked to a single other team since this process began. Were the Red Sox sending his camp signals that they planned to leave him unsigned, Napoli’s agent would be aggressively shopping him in a bid to prove he’s healthy.

But that hasn’t happened, either, so the two sides continue working. Maybe when this is over, the Sox will have upped their average in cases involving prolonged disagreements over a player’s physical condition from .500 to .667, with Napoli joining J.D. Drew, whose shoulder caused a delay of nearly two months before Drew signed in 2007.

Or maybe that average will fall to .333, with Napoli following in the footsteps of Jason Bay, who saw a potential four-year, $60 million extension go up in smoke over the condition of his knees. Bay ended up missing a slew of time with the Mets, but due to concussions.

Whatever the issue with Napoli, the Red Sox can’t exactly be surprised. The rigors of catching only partly explain why he’s managed to top 114 games just once in his career. Even if you gave him an indestructible hip forged from the stoutest titanium, Napoli would be an injury risk. After all, he has missed time to quad, ankle, oblique and shoulder injuries over the years.

LaRoche, on the other hand, has been pretty durable, appearing in at least 141 games in six of his nine seasons. Last year he set a career high in homers (33) and tied one in RBI (100), though his left-handed swing doesn’t fit Fenway Park as well as Napoli’s right-handed one.

The fact that the Red Sox have kept in touch with LaRoche shouldn’t be a shock. They did the same thing with outfielder/first baseman Nick Swisher before he signed with the Indians. They’re smart to cover their bases, particularly if Napoli falls through. They don’t even boast one of his potential internal replacements anymore, since they shipped Jerry Sands to the Pirates in the Joel Hanrahan deal.

At the end of the day, this will all come down to risk, and how much the Red Sox believe they can stomach. If Napoli is indeed their guy, one of these days they’re going to have to prove it or move on.